| Interface Bus A | 
RS485, CS31 protocol, electrically isolated from other electronic. | 
| Interface Bus B | 
RS485, CS31 protocol, electrically isolated from other electronic. | 
| Address switches | 
Two rotary switches for setting the CS31 Bus address (00d to 99d). | 
| I/O Bus | 
I/O Bus to connect S500-I/O modules (max. 7). | 
| Digital inputs/outputs | 
16 configurable digital inputs/outputs in one group: 24 V DC, 0.5 A (max.), short-circuit and overload protected. | 
| High-speed counter | 
Integrated, with many configurable operating modes. | 
| LED displays | 
For system statuses, signal statuses, errors and power supply. | 
| External power supply | 
Via UP and ZP terminal (process voltage: 24 V DC). |